Coal pulverizer monitoring system and associated methods

ABSTRACT

A coal pulverizer monitoring system and method measures a displacement of wheels in a vertical roll wheel pulverizer using strain gauges bonded to tension rods in an ambient environment outside the hostile environment of the milling area of the pulverizer. Signals from the strain gauges reflecting strain on the tension rods are converted to a displacement of the wheels inside the pulverizer, and thus a coal bed height.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/758,934 for Coal Pulverizer Monitoring System and Associated Methodshaving filing date Jan. 31, 2013, the disclosure of which is herebyincorporated by reference herein in its entirety, and commonly owned.

FIELD OF INVENTION

Embodiments of the present invention are generally directed topulverizers and monitoring thereof and in particular to monitoring coalheight and operation of pulverizer components.

BACKGROUND

As is well known in the power generation industry, coal typically usedto generate electricity is dried, pulverized into a fine powder and fedinto a boiler to be burned. The resulting combustion is used to generateheat, then steam and electricity.

A pulverizer is typically used to crush and dry the coal. Coal is fedinto the center of a rotating table. Three metal rollers, hereinreferred to as tires, push down on the table and exert many tons ofpressure onto the table. As the table rotates, the coal moves outwardand under the tires where it is pulverized. During this pulverizingprocess, hot air is blown through the milling area of the pulverizer todry and transport resulting coal dust out of the pulverizer. At the topof the pulverizer, a mechanical classification takes place where anyuncrushed coal is sent back to the center of the table and crushedagain. Any fine grained coal is blown out of the pulverizer.

During the pulverizing process, current (amps) on the table motor ismonitored. A differential gas pressure (typically air plus coal dust)across the milling area of the pulverizer is also monitored. Thesemeasurements are used to approximate physical characteristics of thepulverizer. However, a method or system for measuring the coal bedheight inside the milling area is needed.

It is desirable to accurately measure a level of the coal bed in anonline coal pulverizer. One problem associated with such a task is inpart because of the harsh environment that exists where the coal isbeing pulverized. By way of example, it is desirable to measure theheight of the coal bed inside the coal pulverizer. However, temperaturesinside the pulverizer when it is running typically range between 150-400degrees Fahrenheit. Further, pulverized abrasive coal is constantlybeing blown around inside the pulverizer in a turbulent fashion. It istherefore difficult to provide typical measurement instrumentation,especially typical precision instrumentation that can operate for longperiods of time in such a hostile environment.

SUMMARY

Embodiments of the invention, as herein described by way of example,measure a displacement of rollers in a vertical roll-wheel coalpulverizer. One or more strain gauges may be bonded to one or moretension rods of a coal pulverizer such that strain gauge signals areprovided and conditioned to a voltage signal that reflects strain on thetension rod being measured. Using this signal, the strain may becorrelated to displacement of the wheels inside the pulverizer, and thuscoal bed height. The milling process in the pulverizer may be turned onand a real-time wheel displacement or coal bed height monitored orrecorded.

A method aspect of the invention may comprise monitoring a coalpulverizer by bonding a strain gauge to a surface of a tension rod ofthe coal pulverizer and operating the coal pulverizer including rotatingwheels carried within a milling area for pulverizing coal placedtherein, sensing changes in strain signals from the strain gauge, andcorrelating the strain signals to a displacement of the wheels todetermine a coal bed height.

A monitoring system and method according to the teachings of the presentinvention may be used to meet both operational and maintenance relatedobjectives. By way of example, one embodiment may comprise a monitoringsystem for indicating when the rollers or wheels are coming close tobottoming out the springs and this may be tied to a control system ofthe pulverizer as an alarm point. One embodiment may comprise a methodfor determining if a spring frame is unevenly loaded by comparing thestrain in multiple tension rods. Another embodiment may determine howmuch the wheels and table are wearing over time. Yet another may providea method for tuning air flow to the pulverizer and also aid in controlof a boiler systems.

One embodiment according to the teachings of the present invention mayinclude strain gauges mounted in an orientation for measuring an amountof twisting in real-time for the spring frame, wherein measuring thetension on one side of the rod and the compression on the opposite sideof the rod are monitored. Embodiments of the invention taken alone or incombination desirably reduce wear of the pulverizer and thereforedesirably reduce maintenance costs. Failures may be detected before theyresult in a costly correction.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention are described by way of example withreference to the accompanying drawings in which:

FIG. 1 is a diagrammatical illustration a system for determining coalbed height in a coal pulverizer according to the teachings of thepresent invention;

FIG. 2 is a partial cutaway perspective view of a typical coalpulverizer employing a system of the present invention;

FIG. 3 is a diagrammatical illustration of the embodiment of FIG. 1,wherein a coal height within the pulverizer is illustrated, by way ofexample;

FIG. 4 is a diagrammatical illustration of signal collection andprocessing processor according to the teachings of the presentinvention;

FIG. 5 is plot of spring frame deflection versus voltage indicative oftension rod deformation measured by strain gauges placed on a tensionrod operable with the pulverizer of FIG. 1;

FIG. 6 is a combination plot including tension rod temperature, bolttemperature, casing temperature and tension displacement versus time;

FIG. 7 is a combination plot of upper rod temperature, middle rodtemperature, lower rod temperature, ambient temperature, and roddisplacement versus time;

FIG. 8 is a combination plot of an optimum rod measurement location andscaled rod displacement versus time; and

FIG. 9 is a plot of coal bed height versus time during operation of acoal pulverizer.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown by way of illustration and example. However, thisinvention may be embodied in many forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. Like numerals refer to like elements.

One system 10 for monitoring coal being pulverized in a coal pulverizeris herein described by way of example with reference initially to FIGS.1 and 2 may be described as comprising a coal pulverizer 12, alsoreferred to as a mill, including a base 14 and a table 16 having asurface 18 positioned at a fixed distance 20 from the base. The surface18 of the table 16 is dimensioned for receiving coal 22 to be crushed,as illustrated with reference to FIG. 3.

For one embodiment, herein described by way of example, the pulverizer12 comprises a first spring frame 24 and a roller 26, herein multiplerollers also referred to as tires operable for rolling on the surface 18of the table 16. A spring 28, typically multiple springs, biases thefirst spring frame 24 against a second spring frame 30, wherein thefirst spring frame moves closer to the second spring frame through anaction of the roller 26 traveling over coal carried on the surface ofthe table.

With continued reference to FIGS. 1-3, tension rod 32 are connectedbetween the second spring frame 30 and the base 14. For the embodimentherein described by way of example, the tension rod 32 is substantiallyoutside a hostile environment 34 of the spring frames 24, 30, springs28, rollers 26 and the table 16, as illustrated with reference again toFIG. 2.

A strain gauge 36 is bonded directly to the tension rod 32 at a locationoutside the hostile environment 34, as illustrated with reference againto FIG. 2. With reference again to FIG. 1, a processor 38 is operablefor receiving an electrical signal 40 from the strain gauge 36 andprovides a measure of displacement 42 of the first spring frame 24 fromthe second spring frame 30 and thus a height 44 of the coal 22 on thesurface 18 of the table 16 in the hostile environment 34 of the coalpulverizer 12.

With continued reference to FIG. 1, a temperature sensor 46 (herein athermocouple used by way of example) is connected to the tension rod 32proximate the strain gauge 36 and outside the hostile environment 34 fordetermining a temperature of the tension rod. A signal 48 from thetemperature sensor 46 is processed by the processor 38 for affecting themeasure of displacement 42 resulting from temperature. The results maybe reported via a display 50 or reporting means as desired.

For the embodiment of the system 10, herein described by way of example,an algorithm operable with the processor provides the displacement basedon the strain and the temperature according to a relationship ofTCD=(BC*ε)−f(TRT)

Wherein TCD is the displacement presented as a temperature compensateddisplacement; BC is a constant associated with a preselected coalpulverizer; ε is the measured mechanical strain; and f(TRT) is a lengthdimension as a function of the tension rod temperature for thepreselected coal pulverizer.

As will be described later in this disclosure, the processor 38 may beprogrammed to provide the displacement based on wear of structuralelements of the coal pulverizer over time and the effect ondisplacement. As illustrated with reference again to FIG. 2, multipletension rods 32, the strain gauge 36 may comprise a plurality of straingauges operable with each tension rod and the processor 38.

As is well known in the art, tension rods 32 of a coal pulverizer 12 areconstantly under tension and pull down on the upper, second spring frame30 which then in turn compresses the springs 28 and ultimately pushes onthe pulverizer table surface 18 using the rollers 26. As illustratedwith reference again to FIG. 2, the tension rods 32 are typicallyconnected to a concrete foundation as the base 14 through a lockedhydraulic loading cylinder assembly. The tension rod 32 itself islocated on the outside of the coal pulverizing hostile environment 34.As above described, the spring frames 24, 30, springs 28, tires 26 andtable 16 are all located inside the harsh/hostile environment 34 of thepulverizer 12. As a result, the tension rods 32 are in a desirablelocation for instrumentation and would not be exposed to the hightemperatures or abrasive pulverized coal.

There is a relationship between the strain in the tension rod 32 and thedeflection of the pulverizer rollers/tires 26. As the tension rod 32stretches, the strain gauge 36 produces an output, the signal 40,proportional to the strain in the tension rod. In the milling area ofthe pulverizer, if the rollers, typically solid metal tires, start tomove upward, as a result of the coal bed height 44 increasing, therollers 26 and lower/first spring frame 24 move upward and push againstthe springs 28 which themselves push against the upper/second springframe 30, as illustrated with reference again to FIG. 3. With theupper/second spring frame 30 fixed in place by the tension rods 32(generally at least three), the tires 26 move upward, the springs 28compress and the strain in the rods 32 increases.

For a typical pulverizer 12, there are multiple tension rods 32. Asabove illustrated, a strain gauge 36 may be placed on one or a pluralityof the rods 32 as desired without departing from the teachings of thepresent invention. Further, there are typically multiple springs 28, asillustrated with reference again to FIG. 2.

As illustrated with reference to FIG. 4, one prototype embodiment of thesystem 10 included instrumenting one tension rod 32 with a standardmultipurpose strain gauge 36. A strain gauge amplifier 54 includingsignal processing and a microcontroller 56 forms the processor 38.Further, a data logger 58 was employed. The system 10 was setup when thepulverizer 12 was out of service and void of the coal 22. The straingauge 36 bonded to the tension rod 32 is connected to the strain gaugeamplifier 54. A second strain gauge 36A is bonded next to the firststrain gauge 36 in an opposite axis orientation and also connected tothe amplifier 54 for providing wire length and temperature compensation.The signals from the gauges 36, 36A are fed to an on-board wheat-stonebridge 60 of the amplifier 54. The purpose of the second strain gauge36A and wheat-stone bridge 60 is to cancel effects from temperature atthe strain gauge 36 and wire length compensation. The wire and straingauges were shielded from EMF effects. The signal from the amplifier 54included a millivolt signal and was sent to the processing unit 54 forcalculation into a displacement and then sent to the data logger 58. Asthe tension rod 32 stretched, the data logger 58 would see a change indisplacement. By way of non-limiting example, the millivolt signal couldbypass the processing unit and go directly to the data logger for rawsignal logging.

Performance parameters and measurement relationships were developedbased on empirical data for one typical particular pulverizer. By way ofexample, a voltage response to actual deflections of the pulverizertires was determined. The resulting relationship is presented as a curveand estimated to be linear based on the fact that the pulverizer haslinear styled springs and behaves according to a traditional springequation F=kx, where F is a force, x is a displacement, and k is thespring constant. To verify the linear relationship, and by way ofnon-limiting example, voltage was recorded when the mill had 2000 lbs.of force on each tension rod and when the tires were directly on thetable. Measurements were made and recorded at the spacing 42 between theupper and lower spring frame. The force in each rod was doubled, andmeasurement steps repeated. For the example herein presented by way ofexample, measurements were made at ten various conditions and thenplotted on a graph to verify that the relationship was linear, asillustrated with reference to FIG. 5.

This curve was also used to develop a plot for voltage vs. bed heightfor the pulverizer. Once this plot is developed, an equation isdetermined in order to provide the coal bed height 44 for a givenvoltage. As further described, temperature compensation resulting fromstructural changes are provided for determining a temperaturecompensated coal bed height measurement.

By way of example, the strain and temperature are used to calculate coalbed height inside the pulverizer according to the following relationshipof Equation 1:TCD=(BC*ε)−f(TRT)−f(time and coal hardness)

Wherein TCD=Temperature Compensated Displacement resulting from thermalgrowth of structural elements; BC=Constant; ε=Measured MechanicalStrain; and TRT=Tension Rod Temperature.

The variable TCD is the real temperature compensated displacement of thesprings inside the pulverizer. This means that if coal is forcedunderneath the wheels during operation, the spring frame will be pushedup in-turn displace the springs. Thus, TCD is the same value as coal bedheight.

Phase one of research and development included using part of Equationone to calculate coal bed height. Phase two includes the use of thethird term in Equation one, “f(time and hardness)” to compensate forpulverizer wheel wear over extended lengths of time and Phase threeincludes using more than one tension rod per mill to alarm previouslymentioned anomalies.

During testing, the system included one strain gauge placed on one ofthe three tension rods of the mill. It was understood that under normaloperation of the mill, all three tension rods will have approximatelythe same strain placed on them. The only time this would not be the caseis if a mechanical member failed and/or some foreign object was feedinto the mill and/or the springs were not tensioned evenly during setup.These are special cases and depart from the coal bed height measurement(Phase one), but will be of interest for the Third phase of development.The Third phase will be detailed later, and will include using the abovesystem and processing for all three tension rods in order to provide analarm when a mechanical failure occurs, resulting from foreign debris orunbalanced spring frame loading based on a deviation in theirmeasurement, by way of example.

As above illustrated, the computation of TCD which is equal too coal bedheight requires three components:

Component 1: (BC*ε)=non-temp compensated spring displacement Component2: f(TRT)=perceived spring displacement due to only temp.

Component 3: f (time and coal hardness)=perceived displacement fromwear.

Thus, if you compute component 1 and subtract component 2 and component3 therefrom, the result will be an actual measurement of coal bedheight.

Component 1 represents the non-temp compensated spring displacement.This can also be referred to as x. It is understood that component 2 isdistinguished from the temperature compensation provided by the bridgecircuit described above.

As described above, in order to calculate x, the constant BC has to bemultiplied by the strain output from the amplifier/filter.x=(BC*ε)=component 1=units of length

The constant BC is specific to a single pulverizer. It can be calculatedanalytically or derived through empirical testing. In order toaccurately calculate analytically, one would have to know the exactgeometry and material properties of every component in the mill thattransfers load of the springs. One would also need lab tested springconstants of every spring in the pulverizer. Due to this complexity,empirical testing was chosen as a practical means to find BC. The unitsof BC are of length.

In order to find BC empirically, the equation of component 1 isrearranged as:BC=x/ε

In order to find the term x and ε, several steps take place. The mill iscleaned and ready for service. The strain gauge output is calibrated tozero. The spring displacement at this zero strain is measured. Oncethese steps are completed, a measureable amount of tension is placed onthe rods using standard maintenance equipment. The new output from thestain amplifier/filter will represent ε in the equation above. Thedifference from the old spring displacement and the new springdisplacement will represent x in the equation above. With these twoterms BC can be computed.

By way of example for the springs herein represented, only one datapoint is necessary to calculate BC because the springs in the pulverizerare linear springs. The linearity was not just an assumption but wasproven during hands-on testing by calculating BC over five separate datapoints. Every new data point was measured at a higher tension. Theresults were plotted and proved the linearity.

Once you have BC for a mill, it can then be used to calculate component1 in equation 1 using the strain output from the amplifier/filter alsoknown as ε.

Component 2 is the perceived spring displacement due to temperature. Theneed for component 2 was discovered during testing because ofmeasurement drift that was occurring with the pulverizer when out ofservice due to ambient temperature changes. This drift was due totemperature changes in the mechanical load components because of theambient temperature changes. It was proven through testing that thetension rod was an optimum location in the load transmission path of themill to compute the displacement due to temperature.Component 2=f(TRT)=units of length

Just as for BC, component 2 can be derived analytically or throughempirical testing. If it is to be derived analytically, one would needto be able to predict all the heat fluxes for all the mechanicalcomponents in the load transmission path. One would also need the exactgeometry and material properties of those same components. In practice,the analytical derivation would be possible, but impractical.

Component 2 will return the perceived spring displacement due totemperature only. In order to derive f(TRT) empirically, the mill iscleaned and ready for service. The temperature of the tension rod ismeasured continuously throughout the test. Once ready, the mill isheated up, just as though it was in service but without feeding coal tothe mill and without turning on the pulverizer. The data are plotted anda curve fit to the data represents perceived spring displacement as afunction of TRT. Alternatively, a matrix could be used in place of thecurve fit in order to generate component 2.

Once the f(TRT) is generated, temperature of the tension rod is used tocompute the perceived spring displacement and subtracted from componentone in order to calculate the TCD. This is without accounting forpulverizer mechanical component wear compensation, herein referred to ascomponent 3.

Component 3 is perceived spring displacement from wear. This componentis a function of mill runtime and coal hardness.Component 3=f(time and coal hardness)=units of length

It will approximate the change in measured spring displacement due topulverizer tire, spring, table and other mechanical component wear.Generally, this component should not be necessary if BC and f(TRT) arecalibrated annually because the wear is typically significant overrelatively long periods of time. Thus, component 3 improves the accuracyover long periods of time for operation of the mill, but is an optionalparameter and while useful is not absolutely necessary. Once thecomponent 3 is derived, time and coal hardness can be used to calculatethe perceived spring displacement from wear and will be subtracted fromcomponent 1 minus component 2.

Testing for supporting the above approach was conducted while notincluding component 3, tire wear. Measurements were made with thepulverizer fed with coal and with coal removed. The pulverizer wasloaded and unloaded. Measurements were seen to track upwardly on thedata logger and back down during “sweeping” of the pulverizer, whereinas the milling area was sweeping. As will be understood by those ofskill in the art, as the milling area cooled, the measurement changed.After the pulverizer had cooled, the resulting calculations indicatedthat there was ¾″ of a coal bed still in the milling area. After openingthe pulverizer, the coal bed was measured and there was exactly ¾″ ofcoal under the tire.

Adverse temperature effects to the measurement and monitoringembodiments are eliminated. With instrumentation configured to cancelout temperature effects to the strain gauge setup, temperature effectsresulting from thermal expansion are addressed and components affectingmeasurement identified by placing thermocouples throughout thepulverizer. By way example, thermocouples were placed on the tensionrod, the case of the pulverizer, the top of the spring frame, the bolton the yoke assembly and a thermocouple was arranged to measure ambienttemperatures. During the test and evaluation process, the spring framedisplacement strain gauge was maintained in place to comparethermocouple temperatures to perceived deflection. The pulverizer washeated up without containing coal. Temperature measurements includingdeflections over time were logged based on measured deflections.Examination of resulting data revealed that the tension rod itselfincluded the only temperature that tracked with the perceiveddeflection, as illustrated with reference to FIG. 6, by way of example,including tension rod temperature, bolt temperature, casing temperatureand tension displacement versus time, by way of example.

A follow-up thermal test was performed where thermocouples were placedat various locations on the tension rod to determine if one particularlocation on the tension rod represented the perceived deflection morethan another. A goal was to develop an algorithm that canceled thermalexpansion from the displacement measurement using a thermocouple andspecific location. Measurements of ambient temperature were alsoperformed. The pulverizer was again heated up without turning on itstable motor and without feeding coal into the milling area. It wasobserved that all locations on the tension rod having thermocouples werealmost identical in representing a perceived displacement variation. Thetracking was provided in an inverted and scaled manner, as illustratedwith reference to FIG. 7 including upper rod temperature, middle rodtemperature, lower rod temperature, ambient temperature, and roddisplacement versus time, by way of example.

A formulation developed to invert and bias the displacement measurementto compare displacement as a function of temperature of the tension rodat the strain gauge was developed. A test was performed for verificationpurposes and to confirm that all development thus far was consistent.

Analysis of resulting data resulted in an ability to compare thedisplacement and inverted/scaled performance to temperatures atdifferent locations to determine which temperature most accuratelyrepresented the thermal expansion of the system. As a result, plots ofan optimum rod measurement location and scaled rod displacement versustime were possible, as illustrated with reference to FIG. 8.

Based on these results, the algorithm, as above described, was developedfor calculating the actual bed height displacement after being correctedfor thermal expansion. This equation uses the spring frame deflectioncalculated and described above using the stain gauge with the BCconstant and the temperature at the tension rod to accurately calculatebed height regardless of mill temperature.

During testing, the spring frame displacement was calculated using thestrain gauge located on the tension rod and the techniques discussedabove. Temperatures at the tension rod were also measured. Thepulverizer was placed in service as normal and taken out of service. Asillustrated with reference to FIG. 9, results were found to be asdesired. Once the pulverizer was taken out of service, it was noted thatthe bed height indicated 0.9″. The doors on the pulverizer were openedand it was confirmed that there was almost an inch of coal under thetire. The system and method according to the teachings of the presentinvention proved to be fruitful and actuate. The logger andinstrumentation were operable with the pulverizer for several weeks formonitoring, and resulted in consistent performance by the measurementand monitoring system herein described by way of example.

It is of interest to note that several weeks into the testing, resultingdata showed a spike in the bed height every few seconds. The pulverizerwas taken out of service and emptied. A large piece of steel(approximately 13″×7″×1″) was found inside the pulverizer. The tiresmust have kept running over the piece of steel and it is not clear thatthis precursor to damage would have been found if it were not for thebed height instrumentation. As seen, the embodiment herein presented formeasuring bed height, can also be used to provide an indication of aproblem such foreign material in the pulverizer like the a piece ofsteel.

During the physical installation and setup of the coal bed height systemdevice, it is practical to have the pulverizer emptied, opened and thetension removed from the rods. By way of example, one installationmethod may begin by bonding the thermocouples to the tension rod atdesired locations.

By way of further example, the monitoring system is ready to developconstants for the above described equations. The tension will first needto be removed from the tension rods. Then the tire height above thetable will need to be measured if not at a zero position, and if not atzero would be added to spring frame deflection. The gap between theupper and lower spring frame is to be measured. This will be the firstdata point on the linear curve for strain gauge voltage vs. displacementabove discussed with reference to FIG. 5. By way of example, it isdesirable to place half of the normal preload on the tension rodsbecause of the linear relationship. The displacement and voltage arethen noted and become the second point on the curve of FIG. 5. This willall be repeated at the normal running tension rod preload to get a thirdpoint on the curve. The pulverizer BC constant can then be calculatedfrom the curve for the pulverizer of interest. Only two data points arerequired because of the verification of linearity performed in theprevious section.

The data last to be calculated are used for the f(TRT) equation. Toconstruct the equation above described, the pulverizer will need to beheated up and cooled down without turning on the motor or feeding coalinto the pulverizer. The perceived bed height is logged along with thetension rod temperature. Using these data, the f(TRT) can then becalculated.

Although the invention has been described relative to various selectedembodiments herein presented by way of example, there are numerousvariations and modifications that will be readily apparent to thoseskilled in the art in light of the above teachings. It is therefore tobe understood that, within the scope of the claims supported by thisspecification, the invention may be practiced other than as specificallydescribed.

That which is claimed is:
 1. A system for monitoring coal beingpulverized in a coal pulverizer, the system comprising: a coalpulverizer including: a base: a surface positioned at a fixed distancefrom the base for receiving coal to be crushed thereon; a frame; aroller flexibly biased to the frame for rolling on coal placed thereon;and a tension rod securing the frame to the base; a strain gauge affixeddirectly to the tension rod at a location outside a hostile environmentof the roller; and a processor operable for receiving an electricalsignal from the strain gauge and providing a measure of displacement ofthe roller from the surface, thus a height of coal on the surface of thetable in the hostile environment.
 2. The system according to claim 1,wherein the coal pulverizer further comprises a spring biasing theroller toward the surface, wherein the roller is in a variable spacedposition to the frame through an action of the roller traveling overcoal carried on the surface.
 3. The system according to claim 2, furthercomprising a temperature sensor operable with the tension rod outsidethe hostile environment for determining a temperature thereof, wherein asignal from the temperature sensor is processed by the processor foraffecting the measure of displacement resulting from the temperature. 4.The system according to claim 3, wherein the processor provides thedisplacement based on the strain and the temperature according to arelationship ofTCD=(BC*ε)−f(TRT) wherein TCD is the displacement presented as atemperature compensated displacement; BC is a constant associated with apreselected coal pulverizer; ε is the measured mechanical strain; andf(TRT) is a length dimension as a function of the tension rodtemperature for the preselected coal pulverizer.
 5. The system accordingto claim 4, wherein the processor further provides the displacementbased on perceived deflection due to wear of structural elements of thecoal pulverizer over time and the effect on spring displacement.
 6. Thesystem according to claim 1, wherein the processor comprises a straingauge amplifier having a Wheatstone bridge in electrical contact to thestain gauge, a power supply providing an electrical signal to theWheatstone bridge and a signal conditioner for converting the electricalsignal from the strain gauge to a digital signal operable with acontroller, and wherein the Wheatstone bridge includes a dummy straingauge for cancelling temperature effects at the gauge.
 7. The systemaccording to claim 1, wherein the tension rod comprises multiple tensionrods, and wherein the strain gauge comprises at least one strain gaugeon at least two of the plurality of tension rods.
 8. A system formonitoring coal being pulverized in a coal pulverizer, the systemcomprising: a coal pulverizer including: a base; a table positioned at afixed distance from the base, the table having a surface dimensioned forreceiving coal to be crushed thereon; a first spring frame; a rollerrotatable with the first spring frame and operable for rolling on thesurface of the table; a second spring frame: a spring biasing the firstspring frame against the second spring frame, wherein the first springframe moves closer to the second spring frame through an action of theroller traveling over coal carried on the surface of the table; and atension rod operable with the second spring frame, wherein the tensionrod is fixed to the base, and wherein at least a portion of the tensionrod is outside a hostile environment of the spring frames, spring,roller and table; a strain gauge affixed directly to the tension rod atthe portion thereof; a processor operable for receiving an electricalsignal from the strain gauge and providing a measure of displacement ofthe first spring frame from the second spring frames and thus a heightof coal on the surface of the table in the hostile environment of thecoal pulverizer, wherein the processor employs a spring constant of thespring and strain measured by the strain gauge to determine thedisplacement.
 9. The system according to claim 8, further comprising atemperature sensor operable with the tension rod outside the hostileenvironment for determining a temperature thereof, wherein a signal fromthe temperature sensor is processed by the processor for affecting themeasure of displacement resulting from the temperature.
 10. The systemaccording to claim 9, wherein the processor provides the displacementbased on the strain and the temperature according to a relationship ofTCD=(BC*ε)−f(TRT) wherein TCD is the displacement presented as atemperature compensated displacement; BC is a constant associated with apreselected coal pulverizer; ε is the measured mechanical strain; andf(TRT) is a length dimension as a function of the tension rodtemperature for the preselected coal pulverizer.
 11. The systemaccording to claim 10, wherein the processor further provides thedisplacement based on wear of structural elements of the coal pulverizerover time and the effect on spring displacement.
 12. The systemaccording to claim 8, wherein the processor comprises a strain gaugeamplifier having a Wheatstone bridge in electrical contact to the staingauge, a power supply providing an electrical signal to the Wheatstonebridge and a signal conditioner for converting the electrical signalfrom the strain gauge to a compatible signal operable with a controller,and wherein the Wheatstone bridge includes a dummy strain gauge forcancelling temperature effects at the gauge and from wire lengthemployed.
 13. The system according to claim 12, further comprising acontroller operable for receiving the compatible signal from the straingauge amplifier and the temperature sensor, and wherein the displacementis provided thereby.
 14. The system according to claim 8, wherein thetemperature sensor comprises a thermocouple.
 15. The system according toclaim 14, wherein the thermocouple is attached to the tension rodportion proximate the strain gauge.
 16. The system according to claim 8,wherein the tension rod comprises multiple tension rods, and wherein thestrain gauge comprises a plurality of strain gauges operable with theprocessor.
 17. A method for monitoring a coal pulverizer utilizing acoal pulverizer having a surface positioned at a fixed distance from abase for receiving coal to be crushed thereon, a roller flexibly biasedto a frame for rolling on the surface and coal therebetween, and atension rod securing the frame to the base, the method comprising:bonding a strain gauge to a portion of the tension rod, wherein theportion is located outside a hostile environment of the roller;operating the coal pulverizer for pulverizing coal placed on the surfacethereof; sensing changes in strain signals from the strain gauge;correlating the strain signals to a displacement of the roller; anddetermining a coal bed height therefrom.
 18. The method according toclaim 17, wherein the correlating comprises: receiving an electricalsignal from the strain gauge; providing a measure of displacement of theframe; determining a spring constant of a spring operable between theroller and the frame, wherein the spring constant is a measure of aflexible biasing of the flexibly biased roller; and determining the coalbed height from a combination thereof.
 19. The method according to claim17, further comprising: measuring a temperature of the tension rod;determining an effect of the temperature on the displacementmeasurement; and modifying the coal bed height resulting from theeffect.
 20. The method according to claim 19, wherein the temperaturemeasuring comprises placing a thermocouple on the tension rod forproviding a measure of the temperature.
 21. The method according toclaim 20, wherein the thermocouple placing comprises placing thethermocouple on the tension rod proximate the strain gauge.
 22. Themethod according to claim 19, wherein the displacement measurement isbased on the strain and the temperature according to a relationship ofTCD=(BC*ε)−f(TRT) wherein TCD is the displacement presented as atemperature compensated displacement; BC is a constant associated with apreselected coal pulverizer; ε is the measured mechanical strain; andf(TRT) is a length dimension as a function of the tension rodtemperature for the preselected coal pulverizer.
 23. The methodaccording to claim 22, further comprising determining an effect of wearof structural elements of the coal pulverizer over time and the effecton spring displacement, and modifying the presented displacement basedon the effect of wear.
 24. The method according to claim 17, wherein thestrain gauge bonding comprises bonding a plurality of strain gauges on aplurality of tensions rods operable with the coal pulverizer, andwherein a plurality of strain signals is provided by the strain gaugesfor correlating the plurality of strain signals for determining thedisplacement of the roller and thus the coal bed height determining. 25.The method according to claim 24, further comprising bonding first andsecond strain gauges on opposing sides of each of the plurality oftension rods and comparing the strain measures in each for determiningif the frame is unevenly loaded.
 26. The method according to claim 24,further comprising bonding first and second strain gauges on opposingsides of each of the plurality of tension rods and measuring an amountof twisting of the spring frame by determining a strain on one side ofeach tension rod and compression on the opposing side.
 27. The methodaccording to claim 17, wherein the sensing comprises providing a straingauge amplifier having a Wheatstone bridge in electrical contact withthe strain gauge, providing a power supply for delivering an electricalsignal to the Wheatstone bridge, and using a signal conditioner forconverting the electrical signal from the strain gauge.